Currently, there is no manufacturable method for stamping leadframes for a ceramic quad (CERQUAD) package. The current method for making a CERQUAD leadframe involves etching or stamping a bare Alloy 42 leadframe. Each leadframe is then aluminized either through an electron beam evaporation process (EBEP) or through an ion plating process (IPP). The aluminum is necessary to promote adhesion at the lead tips for the aluminum wire bonds that are used with a ceramic package. However, it is undesirable to have exposed aluminum on leads external to the package body because the aluminum layer complicates a lead finishing process, such as solder or tin plating. Lead finishing of the external leads enables soldering of the leads to a board. Therefore, the EBEP or IPP processes are used to precisely deposit aluminum only at the lead tips of the CERQUAD leadframe. Either of these two processes are very costly in addition to being very slow. The fact that each CERQUAD leadframe must be individually aluminized translates into a long cycle time for making the CERQUAD leadframe. Furthermore, the cost of aluminizing the lead tips of a CERQUAD leadframe accounts for approximately two-thirds of the cost of the leadframe due to the EBEP or IPP process. Although a stamped leadframe traditionally costs less per leadframe as compared to an etched leadframe, the initial cost of a stamping tool is very expensive, so the volume of leadframes produced per stamping tool must be high enough to make the stamping tool cost effective. However, in the case of a CERQUAD leadframe, the price difference between an etched and a stamped bare Alloy 42 leadframe is negligible when compared to the aluminization cost of the lead tips. The major reduction in cost of a CERQUAD leadframe must come from reducing the cost of aluminizing the lead tips.
Leadframes for dual-in-line ceramic packages are less expensive in comparison to CERQUAD leadframes. The surface of the lead tips of dual-in-line leadframes is aluminum clad instead of plated or electron beam deposited. Cladding is an old and well-known process in the art. The cladding process is less expensive than either EBEP or IPP because an aluminum clad stripe is simply rolled onto a bare Alloy 42 strip. The aluminum stripe becomes laminated onto the bare Alloy 42 metal. The aluminum clad Alloy 42 strip can then be stamped into a dual-in-line leadframe. No other aluminization process, such as EBEP or IPP, is required since the lead tips are already aluminum clad. Because the leads are only on two sides of the leadframe, no aluminum is exposed outside of the package body after the device is assembled. Any aluminum clad on the non-leaded siderails is discarded along with the siderails during the trim and form process.
A CERQUAD leadframe would be more cost effective to produce if an aluminum cladding process could be used instead of either the EBEP or IPP process.